Trends in water quality across Ohio watersheds

Transcription

1 Trends in water quality across Ohio watersheds Laura Johnson and Ken Krieger Ohio Water Resources Council Workgroup for Water Resources Monitoring 1 March 1

2 Heidelberg Tributary Loading Program 1 stations Started in 1975 with the and Old Woman Creek probable new addition Up and down of the wetland

3 Colorimetry for TP, DRP, TKN, NH, Si Ion chromatography for NO 3, NO, Cl, Fl, SO Suspended Sediments Samples collected 3x a day Analyzed for all major nutrients and suspended sediments

4 Colorimetry for TP, DRP, TKN, NH, Si Ion chromatography for NO 3, NO, Cl, Fl, SO Suspended Sediments Samples collected 3x a day Analyzed for all major nutrients and suspended sediments

5 Objectives Explore patterns in nutrient export from watersheds in Ohio and Michigan Watershed yield or unit area loads (kg/ha) to correct for differences in watershed size Focus on WY 13 and past 5 years of data Quantify the potential importance of hydrology alongside watershed area and land use

6 Agriculture Hay-Pasture Forest Urban Other % watershed land cover 1 8 Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Watershed area (km ) 15 1 Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater

7 1 Runoff Comparisons across watersheds Runoff (cm) load 5 y maximum 5 y mean 5 y minimum Runoff is similar across watersheds Particularly low in Raisin, Lost, and Tiffin Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater *note only 1y of data for Coldwater

8 1 Runoff Comparisons across watersheds Runoff (cm) load 5 y maximum 5 y mean 5 y minimum Runoff is similar across watersheds Particularly low in Raisin, Lost, and Tiffin Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater *note only 1y of data for Coldwater

9 Total Phosphorus Dissolved Reactive Phosphorus 1.8 Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Unit area load (kg/ha) 5 13 load 5 yr maximum 5 yr mean 5 yr minimum 3 1 Unit area load (kg/ha) Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater 13 load 5 yr maximum 5 yr mean 5 yr minimum. Lake Erie Ohio GL Lake Erie Ohio GL Both TP and DRP are particularly low in Raisin and Tiffin

10 Nitrate-N Comparisons across watersheds 8 Unit area load (kg/ha) 13 load 5 yr maximum 5 yr mean 5 yr minimum Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Nitrate yield is high in Chickasaw and Coldwater Next highest in Portage, Blanchard,, Honey and

11 Why such variation in unit area loads across watersheds? In part due to land use: Agricultural watersheds tended to have higher loads Chickasaw and Coldwater (GLSM) watersheds had consistently high loads, especially nitrate What about influence of flashiness?

12 R-B flashiness index Flashiness = the frequency and rapidity of short-term changes in discharge Incorporates the day-to-day changes in discharge relative to total discharge over the time interval From Baker et al., JAWRA

13 13 load 5 y maximum 5 y mean 5 y minimum Flashiness Comparisons across watersheds R-B index Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Smaller watersheds most flashy Agricultural watersheds as well Raisin and Tiffin have low indices.

14 Influence of agriculture and watershed area on flashiness r=-.53 P< r=-.9 P<.1 R-B index.8.. R-B index % Agriculture Watershed area (km ) *note log scale

15 Influence of flashiness on unit area loads Total Phosphorus Dissolved Reactive Phosphorus Nitrate-N Unit area load (kg/ha) r=.7 P= r=.3 P= r=.587 P= R-B Flashiness index TP and nitrate are significantly related to flashiness The tributary to Lost Creek has lower loads than expected

16 Influence of flashiness on unit area loads Total Phosphorus Dissolved Reactive Phosphorus Nitrate-N Unit area load (kg/ha) r=.8 P< r=.78 P< r=.85 P< R-B Flashiness index Relationships much stronger without Lost Cr tributary Yet, in part driven by Chickasaw and Coldwater, that have high loads because of land management, small watersheds, and high % agriculture

17 Load exported in top 1 and 5% of flows Colored bar Total bar Total Phosphorus Dissolved Reactive Phosphorus Nitrate-N % of the load % of the load % of the load Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater Cuyahoga Raisin Portage Lost Blanchard Tiffin Rock Honey Muskingum Scioto Great Miami Chickasaw Coldwater For all nutrients, most of the load occurs in the top 5% of flow Except the Cuyahoga Small watersheds have higher % exports Point source dominated exports are lower

18 Long-term trends in DRP concentrations yr running average FWMC have been increasing in the and Rivers since the mid-199 s

19 Long-term trends in DRP concentrations *note change in scale Muskingum Cuyahoga

20 Long-term trends in DRP concentrations *note change in scale Scioto Great Miami

21 Long-term trends in DRP concentrations.5.5 *note change in scale Scioto Great Miami

22 Long-term trends in nitrate concentrations FWMC has declined in the and Rivers since the early s

23 Long-term trends in nitrate concentrations *note change in scale Scioto Great Miami

24 Long-term trends in nitrate concentrations *note change in scale Muskingum Cuyahoga

25 DRP DRP chemograph Most agricultural rivers are similar to the Cuyahoga DRP 3 1 Cuyahoga reflects point source inputs As do Great Miami and Scioto Coldwater *note change in scale DRP Coldwater and Chickasaw have the highest concentrations Pattern in Portage is similar but lower magnitude.

26 Nitrate-N Muskingum Nitrate-N *note change in scale Nitrate chemograph June peaks in nitrate across all watersheds, except the Cuyahoga Great Miami and Scioto exhibit similar peaks reflecting mixed sources of nutrients 1 8 Nitrate-N Cuyahoga 3 1

27 Nitrate chemograph Nitrate-N Coldwater Coldwater and Chickasaw peaks are particularly pronounced Nitrate-N Chickasaw 3 1

28 .5 3 GLSM. TP Oct Nov Dec Jan Feb Mar DRP Oct Nov Dec Jan Feb Mar 18 1 Nitrate Oct Nov Dec Jan Feb Mar 1 Water year Chickasaw Creek discharge (m 3 /s) tributaries Added Beaver Creek, outfall of Grand Lake St Marys in October 13 Thus far in WY 1, Chickasaw and Coldwater have much higher DRP and nitrate concentrations than Beaver, TP is similar Indicates substantial processing in the lake Chickasaw Chickasaw Coldwater Beaver

29 Conclusions Unit area loads vary across watersheds based on specific land management practices as well as hydrology Tributaries to GLSM have high loads, especially of nitrate Recent increases in DRP may also be occurring in watersheds outside Lake Erie, though hard to discern from point sources Nitrate may be decreasing across many watersheds, but patterns are still variable Concentrations peak in June even in watersheds with very little agriculture

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31 DRP DRP Portage DRP DRP Great Miami Scioto. DRP. 8 8.

32 DRP Muskingum Coldwater DRP Cuyahoga DRP Chickasaw DRP 3 1..

33 Nitrate-N Nitrate-N Portage Nitrate-N Nitrate-N Great Miami Scioto Nitrate-N 8 8

34 1 8 Nitrate-N Muskingum Nitrate-N Coldwater Nitrate-N Cuyahoga Nitrate-N Chickasaw 3 1